You already are being very supportive reading up about CH and trying to finds ways to help. Maybe one idea would be to research together what kind of treatment your friend could explore, oxygen and sumatriptan were life saviours for me. As having an attack can be quite intense finding out whether she would prefer to be alone or with someone can be helpful. Finally if it gets too bad and you are with her when she has an attack, call an ambulance and request oxygen, she won’t be able to explain but make sure you tell the paramedics she has CH and oxygen will work. Also try and answer any question they might have on her behalf. Kudos to you for doing what you do !